Currently getting this same issue. I've nuked and reinstalled the server, nuked and reinstalled my game client, cleared out %APPDATA%/7 Days to Die, and I'm about out of ideas. This is without EAC enabled.
Here's excerpts from the client and server logs - it won't let me attach text files apparently. From the looks I'd say it's a client issue - Server's just not getting information.
Client:
2021-02-19T16:43:37 12.620 INF Started thread ServerBrowserListUpdater
2021-02-19T16:43:40 14.745 INF Connect by IP
2021-02-19T16:43:40 14.749 INF Connecting to server 10.20.50.147:26900...
2021-02-19T16:43:40 14.749 INF NetPackageManager Init
2021-02-19T16:43:40 14.764 INF NET: LiteNetLib trying to connect to: 10.20.50.147:26900
2021-02-19T16:43:40 14.776 INF NET: LiteNetLib: Connected to server
2021-02-19T16:43:40 14.779 INF Exited thread ServerBrowserListUpdater
2021-02-19T16:43:40 14.781 INF Started thread NCS_Reader_0
2021-02-19T16:43:40 14.781 INF Started thread NCS_Writer_0
2021-02-19T16:43:40 14.801 INF Started thread NCS_Reader_1
2021-02-19T16:43:40 14.801 INF Started thread NCS_Writer_1
2021-02-19T16:43:40 14.805 ERR NCSimple_Deserializer (ch=0):
2021-02-19T16:43:40 14.805 EXC Unknown NetPackage ID: 255
UnknownNetPackageException: Unknown NetPackage ID: 255
at NetPackageManager.getPackageInfoByType (System.Int32 _packageTypeId) [0x00019] in <e9521218400243e9ac8c145545b586cf>:0
at NetPackageManager.ParsePackage (PooledBinaryReader _reader, ClientInfo _sender) [0x00006] in <e9521218400243e9ac8c145545b586cf>:0
at NetConnectionSimple.taskDeserialize (ThreadManager+ThreadInfo _threadInfo) [0x001e5] in <e9521218400243e9ac8c145545b586cf>:0
UnityEngine.DebugLogHandler:Internal_LogException(Exception, Object)
UnityEngine.DebugLogHandler:LogException(Exception, Object)
UnityEngine.Logger:LogException(Exception, Object)
UnityEngine.Debug:LogException(Exception)
Logger:masterLogException(Exception)
Logger:Exception(Exception)
Log:Exception(Exception)
NetConnectionSimple:taskDeserialize(ThreadInfo)
ThreadManager:myThreadInvoke(Object)
System.Threading.ThreadHelper:ThreadStart_Context(Object)
System.Threading.ExecutionContext:RunInternal(ExecutionContext, ContextCallback, Object, Boolean)
System.Threading.ExecutionContext:Run(ExecutionContext, ContextCallback, Object, Boolean)
System.Threading.ExecutionContext:Run(ExecutionContext, ContextCallback, Object)
System.Threading.ThreadHelper:ThreadStart(Object)
(Filename: <e9521218400243e9ac8c145545b586cf> Line: 0)
2021-02-19T16:43:40 14.811 INF Exited thread NCS_Reader_0
2021-02-19T16:43:40 14.811 INF Exited thread NCS_Writer_0
2021-02-19T16:43:59 34.611 INF Exited thread NCS_Reader_1
2021-02-19T16:43:59 34.611 INF Exited thread NCS_Writer_1
2021-02-19T16:43:59 34.631 INF SaveAndCleanupWorld
2021-02-19T16:44:00 34.632 INF [Steamworks.NET] Stopping server
2021-02-19T16:44:00 34.632 INF [Steamworks.NET] Exiting Lobby
Server:
2021-02-19T22:43:40 2782.186 INF NET: LiteNetLib: Connect from: 10.15.0.77:59043
2021-02-19T22:43:40 2782.188 INF Started thread NCS_Reader_5_0
2021-02-19T22:43:40 2782.189 INF Started thread NCS_Writer_5_0
2021-02-19T22:43:40 2782.191 INF Started thread NCS_Reader_5_1
2021-02-19T22:43:40 2782.191 INF Started thread NCS_Writer_5_1
2021-02-19T22:43:40 2782.191 INF [NET] PlayerConnected EntityID=-1, PlayerID='', OwnerID='', PlayerName=''
2021-02-19T22:43:40 2782.193 INF NPCID.Write
2021-02-19T22:43:40 2782.683 INF Time: 41.66m FPS: 20.00 Heap: 1212.4MB Max: 1240.3MB Chunks: 0 CGO: 0 Ply: 0 Zom: 0 Ent: 0 (0) Items: 0 CO: 0 RSS: 2884.2MB
2021-02-19T22:44:00 2802.037 INF NET: LiteNetLib: Client disconnect from: 10.15.0.77:59043 (RemoteConnectionClose)
2021-02-19T22:44:00 2802.037 INF [NET] PlayerDisconnected EntityID=-1, PlayerID='', OwnerID='', PlayerName=''
2021-02-19T22:44:00 2802.037 INF Disconnected player not found in client list...
2021-02-19T22:44:00 2802.038 INF Player disconnected: EntityID=-1, PlayerID='', OwnerID='', PlayerName=''
2021-02-19T22:44:00 2802.038 INF Exited thread NCS_Reader_5_0
2021-02-19T22:44:00 2802.038 INF Exited thread NCS_Reader_5_1
2021-02-19T22:44:00 2802.038 INF Exited thread NCS_Writer_5_0
2021-02-19T22:44:00 2802.039 INF Exited thread NCS_Writer_5_1
2021-02-19T22:44:10 2812.699 INF Time: 42.16m FPS: 20.00 Heap: 1208.0MB Max: 1240.3MB Chunks: 0 CGO: 0 Ply: 0 Zom: 0 Ent: 0 (0) Items: 0 CO: 0 RSS: 2884.1MB